package rsa;

/**
 * @Description: TODO(用一句话描述该文件做什么)
 * @author luoxiaohui
 * @date 2016年8月15日 下午3:48:03
 */

import javax.crypto.Cipher;


import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.math.BigInteger;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.KeyStore;
import java.security.SecureRandom;
import java.security.cert.Certificate;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateCrtKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.Enumeration;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;


public class RSAEncrypt {

  /** 指定加密算法为DESede */
  private static String ALGORITHM = "RSA";
  /** 指定key的大小 */
  private static int KEYSIZE = 1024;
  /** 指定公钥存放文件 */
  private static String PUBLIC_KEY_FILE = "public.keystore";
  /** 指定私钥存放文件 */
  private static String PRIVATE_KEY_FILE = "private.keystore";

  /**
   * 生成密钥对
   */
  private static void generateKeyPair() throws Exception {
    /** RSA算法要求有一个可信任的随机数源 */
    SecureRandom sr = new SecureRandom();
    /** 为RSA算法创建一个KeyPairGenerator对象 */
    KeyPairGenerator kpg = KeyPairGenerator.getInstance(ALGORITHM);
    /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */
    kpg.initialize(KEYSIZE, sr);
    /** 生成密匙对 */
    KeyPair kp = kpg.generateKeyPair();
    /** 得到公钥 */
    Key publicKey = kp.getPublic();
    /** 得到私钥 */
    Key privateKey = kp.getPrivate();
    /** 用对象流将生成的密钥写入文件 */
    ObjectOutputStream oos1 = new ObjectOutputStream(new FileOutputStream(PUBLIC_KEY_FILE));
    ObjectOutputStream oos2 = new ObjectOutputStream(new FileOutputStream(PRIVATE_KEY_FILE));
    oos1.writeObject(publicKey);
    oos2.writeObject(privateKey);
    /** 清空缓存，关闭文件输出流 */
    oos1.close();
    oos2.close();
  }

  /**
   * 生成密钥对字符串
   */
  private static void generateKeyPairString() throws Exception {
    /** RSA算法要求有一个可信任的随机数源 */
    SecureRandom sr = new SecureRandom();
    /** 为RSA算法创建一个KeyPairGenerator对象 */
    KeyPairGenerator kpg = KeyPairGenerator.getInstance(ALGORITHM);
    /** 利用上面的随机数据源初始化这个KeyPairGenerator对象 */
    kpg.initialize(KEYSIZE, sr);
    /** 生成密匙对 */
    KeyPair kp = kpg.generateKeyPair();
    /** 得到公钥 */
    Key publicKey = kp.getPublic();
    /** 得到私钥 */
    Key privateKey = kp.getPrivate();
    /** 用字符串将生成的密钥写入文件 */

    String algorithm = publicKey.getAlgorithm(); // 获取算法
    KeyFactory keyFact = KeyFactory.getInstance(algorithm);
    BigInteger prime = null;
    BigInteger exponent = null;

    RSAPublicKeySpec keySpec = (RSAPublicKeySpec) keyFact.getKeySpec(publicKey, RSAPublicKeySpec.class);

    prime = keySpec.getModulus();
    exponent = keySpec.getPublicExponent();
    System.out.println("公钥模量：" + HexUtil.bytes2Hex(prime.toByteArray()));
    System.out.println("公钥指数:" + HexUtil.bytes2Hex(exponent.toByteArray()));

    System.out.println(privateKey.getAlgorithm());
    RSAPrivateCrtKeySpec privateKeySpec = (RSAPrivateCrtKeySpec) keyFact.getKeySpec(privateKey, RSAPrivateCrtKeySpec.class);
    BigInteger privateModulus = privateKeySpec.getModulus();
    BigInteger privateExponent = privateKeySpec.getPrivateExponent();

    System.out.println("私钥模量：" + HexUtil.bytes2Hex(privateModulus.toByteArray()));
    System.out.println("私钥指数:" + HexUtil.bytes2Hex(privateExponent.toByteArray()));

  }

  /**
   * 加密方法
   * source： 源数据
   */
  public static String encrypt(String source) throws Exception {
    generateKeyPair();
    /** 将文件中的公钥对象读出 */
    ObjectInputStream ois = new ObjectInputStream(new FileInputStream(PUBLIC_KEY_FILE));
    Key key = (Key) ois.readObject();
    ois.close();

    String algorithm = key.getAlgorithm(); // 获取算法
    KeyFactory keyFact = KeyFactory.getInstance(algorithm);
    BigInteger prime = null;
    BigInteger exponent = null;
    if ("RSA".equals(algorithm)) { // 如果是RSA加密
      RSAPublicKeySpec keySpec = (RSAPublicKeySpec) keyFact.getKeySpec(key, RSAPublicKeySpec.class);
      prime = keySpec.getModulus();
      exponent = keySpec.getPublicExponent();

      System.out.println("公钥模量：" + HexUtil.bytes2Hex(prime.toByteArray()));
      System.out.println("公钥指数:" + HexUtil.bytes2Hex(exponent.toByteArray()));

    }

    /** 得到Cipher对象来实现对源数据的RSA加密 */
    Cipher cipher = Cipher.getInstance(ALGORITHM);
    cipher.init(Cipher.ENCRYPT_MODE, key);
    byte[] b = source.getBytes();
    /** 执行加密操作 */
    byte[] b1 = cipher.doFinal(b);
    BASE64Encoder encoder = new BASE64Encoder();
    return encoder.encode(b1);
  }

  /**
   * 解密算法
   * cryptograph:密文
   */
  public static String decrypt(String cryptograph) throws Exception {
    /** 将文件中的私钥对象读出 */
    ObjectInputStream ois = new ObjectInputStream(new FileInputStream(PRIVATE_KEY_FILE));
    Key key = (Key) ois.readObject();

    String algorithm = key.getAlgorithm(); // 获取算法
    KeyFactory keyFact = KeyFactory.getInstance(algorithm);
    RSAPrivateCrtKeySpec privateKeySpec = (RSAPrivateCrtKeySpec) keyFact.getKeySpec(key, RSAPrivateCrtKeySpec.class);
    BigInteger privateModulus = privateKeySpec.getModulus();
    BigInteger privateExponent = privateKeySpec.getPrivateExponent();

    System.out.println("私钥模量：" + HexUtil.bytes2Hex(privateModulus.toByteArray()));
    System.out.println("私钥指数:" + HexUtil.bytes2Hex(privateExponent.toByteArray()));

    /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */
    Cipher cipher = Cipher.getInstance(ALGORITHM);
    cipher.init(Cipher.DECRYPT_MODE, key);
    BASE64Decoder decoder = new BASE64Decoder();

    byte[] b1 = decoder.decodeBuffer(cryptograph);
    /** 执行解密操作 */
    byte[] b = cipher.doFinal(b1);
    return new String(b);
  }

  public static void main(String[] args) throws Exception {

    generateKeyPairString();

    //		String source = "luoxiaohui";//要加密的字符串
    //
    //		String cryptograph = encrypt(source);//生成的密文
    //		String hexCrypt = HexUtil.bytes2Hex(cryptograph.getBytes(),false);
    //		System.out.println("生成的密文--->"+hexCrypt);
    //
    //		String target = decrypt(HexUtil.hex2String(hexCrypt));//解密密文
    //		System.out.println("解密密文--->"+target);
    //

  }
}









